36 research outputs found
Factorial design optimization and in vivo feasibility of poly(Δ-caprolactone)- micro- and nanofiber based small diameter vascular grafts
Because of the severe increase of mortality by cardiovascular diseases, there has been rising interest among the tissue-engineering community for small-sized blood vessel substitutes. Here we present small diameter vascular grafts made of slow degradable poly(epsilon-caprolactone) nanofibers obtained by electrospinning. The process was optimized by a factorial design approach that led to reproducible grafts with inner diameters of 2 and 4 mm, respectively. Fiber sizes, graft morphology, and the resulting tensile stress and tensile strain values were studied as a function of various parameters in order to obtain optimal vascular grafts for implantation after gamma-sterilization. The influence of polymer concentration, solvent, needle-collector distance, applied voltage, flow rate, and spinning time has been studied. Consequently, an optimized vascular graft was implanted as an abdominal aortic substitute in nine rats for a feasibility study. Results are given following up a 12-week implantation period showing good patency, endothelization, and cell ingrowth
Mechanical Evaluation of HydrogelâElastomer Interfaces Generated through ThiolâEne Coupling
The formation of hybrid hydrogelâelastomer scaffolds
is
an attractive strategy for the formation of tissue engineering constructs
and microfabricated platforms for advanced in vitro models. The emergence
of thiolâene coupling, in particular radical-based, for the
engineering of cell-instructive hydrogels and the design of elastomers
raises the possibility of mechanically integrating these structures
without relying on the introduction of additional chemical moieties.
However, the bonding of hydrogels (thiolâene radical or more
classic acrylate/methacrylate radical-based) to thiolâene elastomers
and alkene-functional elastomers has not been characterized in detail.
In this study, we quantify the tensile mechanical properties of hybrid
hydrogel samples formed of two elastomers bonded to a hydrogel material.
We examine the impact of radical thiolâene coupling on the
crosslinking of both elastomers (silicone or polyesters) and hydrogels
(based on thiolâene crosslinking or diacrylate chemistry) and
on the mechanics and failure behavior of the resulting hybrids. This
study demonstrates the strong bonding of thiolâene hydrogels
to alkene-presenting elastomers with a range of chemistries, including
silicones and polyesters. Overall, thiolâene coupling appears
as an attractive tool for the generation of strong, mechanically integrated,
hybrid structures for a broad range of applications
Factorial design optimization and in vivo feasibility of poly(Δ-caprolactone)- micro- and nanofiber based small diameter vascular grafts
Because of the severe increase of mortality by cardiovascular diseases, there has been rising interest among the tissue-engineering community for small-sized blood vessel substitutes. Here we present small diameter vascular grafts made of slow degradable poly(epsilon-caprolactone) nanofibers obtained by electrospinning. The process was optimized by a factorial design approach that led to reproducible grafts with inner diameters of 2 and 4 mm, respectively. Fiber sizes, graft morphology, and the resulting tensile stress and tensile strain values were studied as a function of various parameters in order to obtain optimal vascular grafts for implantation after gamma-sterilization. The influence of polymer concentration, solvent, needle-collector distance, applied voltage, flow rate, and spinning time has been studied. Consequently, an optimized vascular graft was implanted as an abdominal aortic substitute in nine rats for a feasibility study. Results are given following up a 12-week implantation period showing good patency, endothelization, and cell ingrowth